First ride on the Plasma with a power meter.

Today I’ve got a quick follow-up to yesterday’s blog, in which I discussed a training test ride on my new time trial bike, the Scott Plasma.

One of the great things about Stages Power meters is that they are extremely easy to move from one bike to another. On Tuesday’s ride I neglected move my power meter over to the Plasma, and I regret that I didn’t take the 2 minutes to do so–power data would have been very useful to me in my post-ride analysis. Besides that, I’ve become extremely accustomed to constantly monitoring my power output as I ride. Every time I looked down at my Garmin on Tuesday and saw “Pwr. 3s __W” (my 3 second average power occupies the largest part of my Garmin’s main screen) I almost felt as if I were riding naked.

Yesterday I only had an hour to ride, but before I rolled I made sure to swap out the Plasma’s stock NDS crank arm for the Stages power meter. Two bolts, a dust cover and a quick zeroing–done.

Any time you remove the Stages it’s a good idea to Zero it out when re-installing it. This can be done with your Garmin, or the free Stages app (shown).

I don’t think I could ever go back to training without a power meter: it’s the absolute best bike-related training/speed investment I’ve ever made. If you want to get faster, get a power meter and learn how to use it.

I digress…

Like I said, I only had an hour to ride yesterday, but I decided that wanted to do the same average speed as my Tuesday ride (23.0 MPH). I was curious to see if my predicted power output, which I based on my heart rate and experience, was close to the mark.

I was pretty damn close!

Yesterday’s ride average speed was exactly the same as Tuesday’s: 23.0 MPH. My average heart rate was also nearly identical: 160 BPM yesterday vs 157 BPM on Tuesday. My average power output was 260 watts yesterday, which is mid Zone 3–just as I predicted after Tuesday’s ride. I was was a little higher than my precise 250 watt average watt prediction, but because the route I did yesterday included a number of turn-arounds, that probably accounts for the small difference.

I decided to hit one of the 2-mile laps a little harder than the others, increasing my rolling average from mid-26 MPH to 29 MPH. On that stretch I set a new personal record time, and came within a 9 watts of my lifetime best 4 minute power PR (384 watts).

I’ve ridden this particular 2 mile stretch of road a total of 269 times (thanks for counting, Strava!), but it’s still tough to make a direct comparison to previous efforts. Here’s why…

Yesterday’s time was my fastest on that section of road, but I’ve also never hit it with as many watts as I did yesterday. Yesterday I put down 375 watts on that 2 mile stetch, and the closest I’ve come, historically, on the same segment was 341 watts (my time was 18 seconds slower).

Of course wind is another factor that makes a speed/watts comparison nearly impossible. The wind was fairly mild yesterday, perhaps 4-5 MPH, and it was a crossing tailwind on the segment in question.

Finally, equipment. Yesterday I was on the TT bike, but I was in “slow” training configuration (regular road kit, no shoe covers, standard road helmet, 2 bottle cages/2 bottles, stock non-aero wheelset, Gatorskin Hardshell tires, saddle bag, video camera, rear flasher.) It would be interesting to hit that same section of road under similar conditions and with close to the same wattage output in race configuration (Skinsuit, shoe covers, time trial aero helmet, single bottle cage, Zipp wheelset, race tires, no saddle bag, no rear flasher, no video camera). I’m pretty sure that under similar conditions and wattage output my average speed would be somewhere around 31 MPH with a full blown TT race setup.

The Plasma is definitely doing a good job of transferring power, and it’s very aero. The stock wheelset is fine until I reach speeds over 24 MPH or so, and then I can really feel them dragging compared to my slippery Zipp 404 Firecrest wheels. This is actually a positive, though. After training on these heavy and non-aero wheels, when I race with my Zipps it’s going to feel incredibly fast by comparison.

That’s definitely one of the most common reasons. It makes sense to put most of your miles on a cheap pair of two hundred dollar training wheels instead of an expensive set of $3,000 race wheels. I’ve gone down on a training ride and cracked a Zipp, and it’s not a good feeling. Trashing a $200 pair of wheels is not going to ruin your day.

The main reason I’ll be running the stock wheels on my TT bike training rides, though, is because the Plasma has an 11-speed drivetrain, and my Madone has a 10-speed drivetrain. My Zipps are 10 and 11-speed compatible, but swapping the cassette every time I move them from the Madone to the Plasma (and vice-versa) is a pain. So I’ll just train on the stock wheels, and move the Zipps over to the TT bike for races.

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